The invention relates to a safety device for a percussion fuse in a rifled missile. The firing channel or primer tube which leads from the percussion fuse to a booster charge is blocked by such a safety device and is only unblocked by virtue of inertial forces when certain ballistic flight conditions of the rifled missile have been attained.
Such types of safety devices form part of the state of the art. For example, such a safety device is disclosed in German Pat. No. 844,564. In this patent there is disclosed a percussion fuse for rifled missiles which has a blocking element transversely movably mounted with respect to the ignition channel. Thus the blocking element of this device of the state of the art is movable at right angles with respect to the axis of the fuse and is held in position by means of the supporting spring. Thus the blocking element is held in position by the spring after launching of the missile, as well as during the transport and loading positions of the missile. The blocking element is adapted to assume a blocking position in front of the central bore in which the firing pin is mounted.
This blocking position of the blocking element is also maintained during the acceleration of the missile in the firing tube which occurs after launching. The centrifugal forces imparted to the missile only become fully effective after the missile has left the mouth of the launching tube. Due to the location of the center of gravity of the blocking element, the latter is laterally slidably displaced against the action of the spring. This shift of the center of gravity, which is required for the slidable lateral displacement of the blocking element, is effected by means of providing the blocking element with pockets filled with liquid mercury at each side thereof, by means of which an equilibrium is established. The membrane-cover which seals the pocket is only pierced under the influence of the centrifugal force so that the liquid mercury pours out of the pocket to a hollow space. Since the other pocket remains filled with liquid mercury, there occurs a shift of the center of gravity of the blocking element which in turn produces a shift of the blocking element against the force of the spring, whereby the central bore in which the firing pin is disposed is unblocked so that the firing pin can now hit the pellet-primer upon impact of the missile.
This known blocking element is formed by a slidable element of oval shape. The complementary portion which, jointly with the oval-shaped blocking element, would jointly make for a full circle, is occupied by the supporting spring of the device. In addition thereto, the blocking element is provided with kidney-shaped pockets filled with liquid mercury. The entire construction of the blocking element is therefore quite complicated and expensive. A significant improvement of the safety of the primer tube is not possible with this known fuse because the pouring out of the liquid mercury from one of the pockets occurs without appreciable delay and the surmounting of the spring force during the slidable lateral movement of the blocking element can even take place spontaneously.